People who are incarcerated exhibit high rates of disease, but data evaluating the delivery of medical services to inmates are sparse, particularly for jail settings. We sought to characterize the primary medical care providers for county jail inmates in New York State. From 2007 through 2009, we collected data on types of medical care providers for jail inmates in all New York State counties. We obtained data from state monitoring programs and e-mail questionnaires sent to county departments of health. In counties outside New York City (n = 57), jail medical care was delivered by local providers in 40 counties (70%), correctional medical corporations in 8 counties (14%), and public providers in 9 counties (16%). In New York City, 90% of inmates received medical care from a correctional medical corporation. Larger, urban jails, with a greater proportion of Black and Hispanic inmates, tended to use public hospitals or correctional medical corporations as health care vendors. Jail medical services in New York State were heterogeneous and decentralized, provided mostly by local physician practices and correctional medical corporations. There was limited state oversight and coordination of county jail medical care.